* {margin:0; padding:0; font-family: "microsoft yahei" sans-serif; font-size: 14px;}
.canvas {width:800px;height:600px;overflow: auto;border:1px solid #ccc}
.control-panel {position: fixed; background-color: #fff; right: 5px; top:5px; padding: 10px;}
.button {display: block; padding: 10px; cursor: pointer; border:1px solid #ccc;margin-bottom:15px;}
.button:hover {background-color: #ffa500;}
.nav {padding: 10px; }
.nav a {line-height:180%}

canvas {background-color: #000;/* opacity: .6;width: 1440px;height: 720px*/}